# net.inet.tcp.stats
Plugin: freebsd.plugin
Module: net.inet.tcp.stats
## Overview
Collect overall information about TCP connections.
The plugin calls `sysctl` function to collect necessary data.
This collector is supported on all platforms.
This collector supports collecting metrics from multiple instances of this integration, including remote instances.
### Default Behavior
#### Auto-Detection
This integration doesn't support auto-detection.
#### Limits
The default configuration for this integration does not impose any limits on data collection.
#### Performance Impact
The default configuration for this integration is not expected to impose a significant performance impact on the system.
## Metrics
Metrics grouped by *scope*.
The scope defines the instance that the metric belongs to. An instance is uniquely identified by a set of labels.
### Per net.inet.tcp.stats instance
These metrics show TCP connections statistics.
This scope has no labels.
Metrics:
| Metric | Dimensions | Unit |
|:------|:----------|:----|
| ipv4.tcppackets | received, sent | packets/s |
| ipv4.tcperrors | InErrs, InCsumErrors, RetransSegs | packets/s |
| ipv4.tcphandshake | EstabResets, ActiveOpens, PassiveOpens, AttemptFails | events/s |
| ipv4.tcpconnaborts | baddata, userclosed, nomemory, timeout, linger | connections/s |
| ipv4.tcpofo | inqueue | packets/s |
| ipv4.tcpsyncookies | received, sent, failed | packets/s |
| ipv4.tcplistenissues | overflows | packets/s |
| ipv4.ecnpkts | InCEPkts, InECT0Pkts, InECT1Pkts, OutECT0Pkts, OutECT1Pkts | packets/s |
## Alerts
The following alerts are available:
| Alert name | On metric | Description |
|:------------|:----------|:------------|
| [ 1m_ipv4_tcp_resets_sent ](https://github.com/netdata/netdata/blob/master/src/health/health.d/tcp_resets.conf) | ipv4.tcphandshake | average number of sent TCP RESETS over the last minute |
| [ 10s_ipv4_tcp_resets_sent ](https://github.com/netdata/netdata/blob/master/src/health/health.d/tcp_resets.conf) | ipv4.tcphandshake | average number of sent TCP RESETS over the last 10 seconds. This can indicate a port scan, or that a service running on this host has crashed. Netdata will not send a clear notification for this alarm. |
| [ 1m_ipv4_tcp_resets_received ](https://github.com/netdata/netdata/blob/master/src/health/health.d/tcp_resets.conf) | ipv4.tcphandshake | average number of received TCP RESETS over the last minute |
| [ 10s_ipv4_tcp_resets_received ](https://github.com/netdata/netdata/blob/master/src/health/health.d/tcp_resets.conf) | ipv4.tcphandshake | average number of received TCP RESETS over the last 10 seconds. This can be an indication that a service this host needs has crashed. Netdata will not send a clear notification for this alarm. |
## Setup
### Prerequisites
No action required.
### Configuration
#### File
The configuration file name for this integration is `netdata.conf`.
Configuration for this specific integration is located in the `[plugin:freebsd:net.inet.tcp.stats]` section within that file.
The file format is a modified INI syntax. The general structure is:
```ini
[section1]
option1 = some value
option2 = some other value
[section2]
option3 = some third value
```
You can edit the configuration file using the [`edit-config`](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#edit-a-configuration-file-using-edit-config) script from the
Netdata [config directory](https://github.com/netdata/netdata/blob/master/docs/netdata-agent/configuration/README.md#the-netdata-config-directory).
```bash
cd /etc/netdata 2>/dev/null || cd /opt/netdata/etc/netdata
sudo ./edit-config netdata.conf
```
#### Options
Config options
| Name | Description | Default | Required |
|:----|:-----------|:-------|:--------:|
| ipv4 TCP packets | Enable or disable ipv4 TCP packets metric. | yes | no |
| ipv4 TCP errors | Enable or disable pv4 TCP errors metric. | yes | no |
| ipv4 TCP handshake issues | Enable or disable ipv4 TCP handshake issue metric. | yes | no |
| TCP connection aborts | Enable or disable TCP connection aborts metric. | auto | no |
| TCP out-of-order queue | Enable or disable TCP out-of-order queue metric. | auto | no |
| TCP SYN cookies | Enable or disable TCP SYN cookies metric. | auto | no |
| TCP listen issues | Enable or disable TCP listen issues metric. | auto | no |
| ECN packets | Enable or disable ECN packets metric. | auto | no |